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    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script type="text/javascript">
        //////////////////////////
        function A() { }
        A.prototype.n = 1
        var b = new A()
        A.prototype = {
            n: 2,
            m: 3,            
        }
        var c = new A()
        console.log(b.n, b.m, c.n, c.m)//1,undefined,2/3
        ///////////////////////////////
       
        function Foo() {
            Object.prototype.a = function () {
                console.log('可访问a')
            }
        }
        Function.prototype.b = function () {
            console.log('可访问b')
        }
        var foo = new Foo()
        foo.a();//可访问a
        foo.b();//可访问b
        Foo.a();//可访问a
        Foo.b();//可访问b


        // //////////////////////////////

        var fun = function(){}
        fun.prototype={
            name:'peter',
            age:25
        }
        var a = new fun();
        var b = new fun();
        console.log(a.name,b.name);//peter,peter
        fun.prototype.name = 'jack';
        console.log(a.name,b.name);//jack,jack
        fun.prototype = {};
        fun.prototype.name ='tom';
        console.log(a.name,b.name);//jack,jack
        b.constructor.prototype.name = 'kitty';
        console.log(a.name ,b.name);////jack,jack

    </script>
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